Persons having physical disabilities or infirmities which inhibit their mobility more often have difficulty in standing from a sitting position and in easing themselves into a chair when sitting. A characteristic of the common chair designed for persons without such handicaps is the positioning of the user's weight at back of the seat, thereby relieving the legs from body forces. The act of standing up requires transfer of the user's weight from the back of the chair to his or her legs, which places large stress primarily on the knees and arms as the weight shifts and the body is lifted from the chair. When sitting, the user must be prepared to suddenly shift his or her body weight outside of the normal balanced condition and towards the back of the chair.
Previous attempts to design chairs to assist the seated user in lifting his or her body from the chair when rising to a standing position or in easing the user into a seated position more often have included mechanically or hydraulically, or even electrically tiltable seat portions which are not user-friendly and are often intimidating. Examples of such prior art devices are shown in U.S. Pat. Nos. 3,039,818 (Frank); 3,259,427 (Wiest); 3,679,260 (Morse-Brown); 3,851,917 (Horstmann et al); 4,059,305 (Ammirata); and 4,778,217 (Lane). All are comparatively complicated, expensive, and unattractive, and their specialized features for the purpose constantly remind the user of his or her infirmity.
Other chairs without such operable features are known for assisting a patient to rise from the chair, such as the resilient chairs described in U.S. Pat. Nos. 4,555,139 (Leib) and 4,595,235 (Leib), or for assisting a person who is already sitting in the chair to position the chair forwardly or backwardly as is most comfortable when performing a specific task or resting. See, for example, U.S. Pat. Nos. 4,595,234 (Kjersian) and 4,796,105 (Sheehan et al).
By contrast, it is intended by the present invention to provide a chair which does not have any such mechanically, hydraulically, or electrically movable parts but, rather, utilizes the user's normal movements and shifts in body weight to facilitate his or her sitting down in, and rising from the chair. Thus, no power source will be required, and the assistance to the user will be inherent from the design features of the chair itself. The user will sit or stand using slow, even movements, as is most comfortable for the elderly and the handicapped.
The chair must be relatively stable, comfortable and should comply with the appropriate anthropometric and ergonomic data of the intended user. Further, the chair should be of normal size (i.e., within the confines of a four-foot cube), and its appearance should be simplistic and aesthetically pleasing.